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<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>包装类</title>
</head>
<body>
   <script>
      const str='pink'
      console.log(str.length)
      const num=12
      console.log(num.toFixed(5))
   </script>
</body>
</html>